Add rows after a set of data.

Hello,

I have a large .xlsx file in which I have about a million rows. I have let us say "categories" in Column F.

Here is what I wish to achieve: Design a macro or any other solution that would,
a) Search for the range of duplicate categories.
b) Once the list ends, insert a blank row after that.

Here is an example: The data inputted is like this:-
F
Metal
Metal
Metal
Metal
Metal
Wooden
Wooden
Wooden
Wooden
Wooden
Wooden
Steel
Steel
Natural
Metal
Metal

I want it to be:
Metal
Metal
Metal
Metal
Metal

Wooden
Wooden
Wooden
Wooden
Wooden
Wooden

Steel
Steel

Natural

Metal
Metal

Notes:
1. There are other columns too with data related to column F.
2. I would be glad if I could get detailed instructions as, I am not at all aware with VBA but know basics of VB6 (just the basics).
3. The Office version used is : Office 2007

Regards,
Kshitij

Try:

Sub TryThis()
Dim icell As Long, lastrow As Long

Application.ScreenUpdating = False

lastrow = Range("F" & Rows.Count).End(xlUp).Row

For icell = lastrow To 2 Step -1
    If Range("F" & icell).Value <> Range("F" & icell - 1).Value Then
        Range("F" & icell).EntireRow.Insert Shift:=xlDown
    End If
Next icell
    
Application.ScreenUpdating = True

End Sub

Maybe:

Sub kshtjj()
Application.ScreenUpdating = False
Range("F3").Select
Do Until ActiveCell.Value = ""
    If ActiveCell.Value <> ActiveCell.Offset(1).Value Then
        ActiveCell.Offset(1).EntireRow.Insert
        ActiveCell.Offset(2).Select
    Else
        ActiveCell.Offset(1).Select
    End If
Loop
Application.ScreenUpdating = True
End Sub